Climate-Induced Changes in Year-to-Year Variations in Yields of Major Crops

Tuesday, 16 December 2014
Toshichika Iizumi1, Gen Sakurai1 and Navin Ramankutty2, (1)NIAES National Institute for Agro-Environmental Sciences, Tsukuba, Japan, (2)McGill University, Montreal, QC, Canada
Incidences of climatic extremes and associated crop failures in major food-producing regions have implications for commodity prices and generate concerns for national governments and commercial entities in import-dependent countries. While recent changes in temperature and precipitation extremes are evident, their impacts on the year-to-year variability of yield remain unclear. Here we present a global assessment of the impacts of recent climate change on year-to-year variations in yields of major crops using a global dataset of historical yields recently developed by merging satellite product and country-level crop statistics. We found that crop yield variability, in a large portion (24-53%) of the global harvested area, decreased from the earlier decade (1982—1993) to the later decade (1994—2005). However, yield variability also increased in a substantial portion (9—17%) of the harvested area. The changes in yield variability across 20—31% of the harvested area could be reasonably explained by changes in an agro-climatic index. Our findings reveal that climate change in the last two decades has led to more unstable yields in some regions. However, climate change has reduced yield variability in many more regions of the world. This suggests complex influences of climate change and agronomic technology on yield variability.